Add UID scanner functionality and related infrastructure

- Introduced a new module `uid_scanner` in userspace for managing UID scanning.
- Created a new GitHub Actions workflow for building the `user_scanner`.
- Implemented kernel communication in `throne_comm.c` and `throne_comm.h` to handle user space updates and rescan requests.
- Developed the `uid_scanner` daemon in C to scan user directories and manage UID whitelists.
- Added configuration management for the UID scanner with support for multiple users and auto-scanning.
- Implemented logging and error handling throughout the UID scanning process.
- Created necessary build files for the `user_scanner` JNI integration.
- Added a `.gitignore` file to exclude build artifacts.

userspace/ksud/src/init_event.rs

@@ -1,7 +1,6 @@
 use crate::defs::{KSU_MOUNT_SOURCE, NO_MOUNT_PATH, NO_TMPFS_PATH};
-use crate::kpm;
 use crate::module::{handle_updated_modules, prune_modules};
-use crate::{assets, defs, ksucalls, restorecon, utils};
+use crate::{assets, defs, ksucalls, restorecon, utils, kpm, uid_scanner};
 use anyhow::{Context, Result};
 use log::{info, warn};
 use rustix::fs::{MountFlags, mount};
@@ -35,6 +34,9 @@ pub fn on_post_data_fs() -> Result<()> {
 
     assets::ensure_binaries(true).with_context(|| "Failed to extract bin assets")?;
 
+    // Start UID scanner daemon with highest priority
+    uid_scanner::start_uid_scanner_daemon()?;
+
     // tell kernel that we've mount the module, so that it can do some optimization
     ksucalls::report_module_mounted();